<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS 导航条下拉菜单</title>
    <style>
        ul {
            list-style-type: none;
            margin: 0;
            padding: 0;
            overflow: hidden;
            background-color: #333;
        }

        li {
            float: left;
        }

        li a,
        .dropbtn {
            display: inline-block;
            color: white;
            text-align: center;
            padding: 14px 16px;
            text-decoration: none;
        }

        li a:hover,
        .dropdown:hover .dropbtn {
            background-color: red;
        }

        li.dropdown {
            display: inline-block;
        }

        .dropdown-content {
            display: none;
            position: absolute;
            background-color: #f9f9f9;
            min-width: 160px;
            box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.2);
        }

        .dropdown-content a {
            color: black;
            padding: 12px 16px;
            text-decoration: none;
            display: block;
            text-align: left;
        }

        .dropdown-content a:hover {
            background-color: #f1f1f1
        }

        .dropdown:hover .dropdown-content {
            display: block;
        }
    </style>
</head>

<body>
    <ul>
        <li><a class="active" href="#home">主页</a></li>
        <li><a href="#news">新闻</a></li>
        <li class="dropdown">
            <a href="#" class="dropbtn">下拉菜单</a>
            <div class="dropdown-content">
                <a href="#">链接 1</a>
                <a href="#">链接 2</a>
                <a href="#">链接 3</a>
            </div>
        </li>
    </ul>

    <h3>导航条插入下拉菜单</h3>
    <p>鼠标移动到"下拉菜单"显示列表</p>
</body>

</html>